Objective
To establish turns-amplitude, activity-envelope amplitude and activity-number of small segements (NSS) clouds of normal early teens using interference pattern. Method: Forty four healthy early adolescence from 11 to 15 years old participated in this study. The interference patterns were analyzed using quantitative electromyography of the biceps brachi and tibialis anterior muscles. The interference patterns were measured at 3 to 5 different force levels ranging from minimum to maximum and turns, mean amplitude, activity, envelope amplitude, NSS were analyzed. By turns/amplitude, activity/envelope amplitude and activity/ NSS ratio, normal clouds of gender related each parameters were obtained. Results: The turns-amplitude, activity-envelope amplitude and activity-NSS ratio of the biceps brachii and tibialis anterior muscles were obtained. Normal clouds of gender related turns-amplitude, activity-envelope amplitude and activity-NSS for each muslces were established. Conclusion: By using normal cloud patterns of turns- amplitude, activity-envelope amplitude and activity-NSS, automatic interference pattern analysis may contribute to diagnose neuromuscular disease in early adolescent patients. (J Korean Acad Rehab Med 2007; 31: 333-340)